MC3470

[Tony Duell]

> 
> On 02/02/2008 22:22, Tony Duell wrote:
> >>>  > Also, does anyone have a proper data sheet for the MC3470 (disk read
> >>>  > amplifier etc).
> 
> > However, I still have one unaswered question : There's a DC balance 
> > preset in the differntiator stage. What's the proceue for adjusting it?
> 
> It's to adjust the data symmetry, and for Sony and Apple drives that use 
> a 3470, you adjust it so that the data signal has a 50% mark/space ratio 
> when the input is a constant frequency (125kHz or 250kHz).

Do you mean that? I thought the output (pin 10) pulse width was set byu 
the RC network on pins 8 and 9. Do you really mean that the offset adjust 
preset is used to get all the pulses equally spaced, rather than occuring 
in pairs (which is the most likely result of an imbalance in the cicuit, 
I think).

Or do you adjust for 50% duty cycle at some other point?

-tony